Custom Cache Implementation

Introduction:

                Liferay internally uses EHCache provider for caching mechanism. Normally if we store any object in cache that is expiring after 10 minutes. This is because of default cache declaration in ‘liferay-multi-vm-clustered.xml’.

The path for the above ‘liferay-multi-vm-clustered.xml’ file is,

è  \tomcat-7.0.40\webapps\ROOT\WEB-INF\lib\portal-impl.jar.

Extract the above ‘portal-impl.jar’ file . .

è In ‘Portal-impl\ehcache\liferay-multi-vm-clustered.xml’ the declaration will be as below,

                <defaultCache

                                eternal="false"

                                maxElementsInMemory="10000"

                                overflowToDisk="false"

                                timeToIdleSeconds="600" >  <!-- Time in seconds -->

                                --------------

                </defaultCache>

è In ‘Portal-impl\portal.properties’ the above xml file will be configured as below,

ehcache.multi.vm.config.location=/ehcache/liferay-multi-vm-clustered.xml

Override the default cache:

                To override the default cache behavior i.e., expiration time, Idle time.

1.       Created one folder ‘mycache’ in \tomcat-7.0.40\webapps\ROOT\WEB-INF\classes

2.       Copy the liferay-multi-vm-clustered.xml file from  Portal-impl\ehcache\  and Paste it in \tomcat-7.0.40\webapps\ROOT\WEB-INF\classes\ mycache. There you can change the default behavior as follows,

                 <defaultCache

                                eternal="false"

                                maxElementsInMemory="10000"

                                overflowToDisk="false"

                                timeToIdleSeconds="300"

                             timeToLiveSeconds=”1800”>  <!-- Time in seconds -->

                                --------------

                </defaultCache>

                From the above declaration, stored object in the cache will be expired after 30 minutes. Declared timeToIdleSeconds=”300” means if we don’t access the cache value for 5 minutes it will get expired.

                In case if you want your cache value never get expire just try the following declaration,

                 <defaultCache

                                eternal="false"

                                maxElementsInMemory="10000"

                                overflowToDisk="false"

                                timeToIdleSeconds="0"

                             >  <!-- Time in seconds -->

                                --------------

                </defaultCache>

3.       Configure the above xml file in \tomcat-7.0.40\webapps\ROOT\WEB-INF\classes\portal-ext.properties as follows,

ehcache.multi.vm.config.location=/mycache/liferay-multi-vm-clustered.xml